<!DOCTYPE html>
<html lang="en">
  <head>
    <meta charset="UTF-8" />
    <meta http-equiv="X-UA-Compatible" content="IE=edge" />
    <meta name="viewport" content="width=375" />
    <title>Document</title>
    <style>
      * {
        margin: 0;
        padding: 0;
      }

      #box {
        width: 345px;
        height: 150px;
        margin: 15px;

        background-color: red;
      }
    </style>
  </head>
  <body>
    <div id="box"></div>
  </body>
</html>
